Automated deck bushing system

ABSTRACT

A drilling system including a drill bit. A deck bushing includes an outer housing and an inner sleeve rotatably arranged in the outer housing, the inner sleeve having an inner diameter wider than a width of the drill bit. A drop-in sleeve is configured to be inserted into the inner sleeve of the deck bushing. At least a portion of the drop-in sleeve engages the inner sleeve of the deck bushing such that a friction between the drop-in sleeve and inner sleeve of the deck bushing causes the drop-in sleeve and inner sleeve of the deck bushing to rotate together. A lifting sub configured to be inserted into the drop-in sleeve.

FIELD OF THE INVENTION

The invention relates to earth boring rotary drilling assemblies and, in particular to drilling assemblies that utilize a deck bushing.

BACKGROUND OF THE INVENTION

Earth drilling equipment is subjected to tremendous forces while in use. As a result, many elements of the earth drilling equipment frequently need replacement. Elements of earth drilling equipment are robust structures typically having great mass.

Elements of a typical drilling assembly can include a drill string including a plurality of drill pipes, a bit sub attached to the end of the drill pipe, and a drill bit. The earth drilling assembly also includes elements for supporting and operating the drill, such as a deck and a deck bushing that provides horizontal stabilization to the drill string as the drill string passes through the deck of the drilling assembly.

Due to the stresses experienced by elements of earth drilling equipment, the elements may need frequent maintenance and/or replacement. Such elements are typically referred to as “consumables”. For example, drill bits typically wear out relatively quickly are typically the most frequently changed portion of a drilling assembly. Additionally, the deck bushing is another portion of a drilling assembly that can require frequent changing.

Repair, maintenance and replacement of elements of a drilling assembly have a number of associated issues. For example, any time that elements of a drilling assembly are being repaired, maintained or replaced, the drilling assembly is not operational, personnel are idle. Changing parts, such as a drill bit or deck bushing can be quite time consuming. Any time that a drilling assembly is not operational, money is being lost.

Additionally, elements of a drilling assembly tend to have large masses. As a result, handling elements of a drill assembly can be dangerous to operators. This is particularly the case when a number of elements must be handled at the same time, such as when a drill bit is changed. Workers can be injured or die when performing maintenance or replacement operations. For example, soft tissue and hand injuries, leading to amputation or death can result from workers being impacted by or pinned between elements of a drilling assembly.

As a result, there are a number of regulations that must be complied with and safety precautions taken when operating a drill, and particularly when carrying out certain operations. For example, common sense and good judgment must be employed and safety equipment utilized, such as hard hats, gloves, wearing work clothing, such as safety shoes or boots, and wearing goggles. Workers should never be under the influence of drugs, alcohol or medication. Appropriate training and qualifications must be obtained. Only physically able workers should be utilized. Correct equipment, such as properly sized equipment and maintained, should be utilized.

One operation that must be frequently performed can be particularly dangerous and require a great deal of work is changing a drill bit. A bit changing operation utilizing current technology starts as illustrated in FIG. 1. Changing a drill bit with this technology requires raising a drill string 1 and deck bushing 3 to ensure that there is a safe and comfortable working clearance for operators to install a deck bushing lifting ring 5 in the opening 7 in the drilling deck 9 in which the deck bushing normally sits.

The top surface 9 and counter bore surface 11 of the deck must be completely cleaned off and the deck bushing lifting ring 5 installed, as shown in FIG. 2. The drill string 1 is lowered to ensure that the deck bushing 3 seats properly within the deck bushing lifting ring 5 and that desired wrench flats 13 properly positioned. In one embodiment, the wrench flats are approximately one meter from the deck of the drill, as shown in FIG. 3.

A deck bushing retaining clamp 15 is then attached to the drill string 1. This operation begins with unscrewing a male threaded bolt handle 17 and adjusting a female threaded bolt handle 19 until a flat-to-flat 21, 23 distance 25 is equal to or slightly greater than a distance of desired wrench flats 13 on the drill string 1, as shown in FIG. 4. The deck bushing retaining clamp 15 is then opened, as shown in FIG. 5. In this and any of the steps in this operation, it is important to keep fingers away from rotating and moving parts.

As shown in FIG. 6, the deck bushing retaining clamp 15 is then installed about the drill string on the wrench flats, as shown in FIG. 6. The bottom surfaces of the deck bushing retaining clamp 15 should sit evenly on shoulders of the wrench flats. The bolt handles are manually tightened. As the bolts are tightened, it should be ensured that the deck bushing retaining clamp is parallel to the deck of the drill and is firmly secured to the drill string.

After attaching the deck bushing retaining clamp to the drill string, the height and orientation of the drill pipe may be adjusted to allow swivel hooks 27 on the deck bushing retaining clamp to be attached to lifting handles 29 on the deck bushing lifting ring. The hooks are attached such that the swivel hooks are directed outwardly. FIG. 7 illustrates the deck bushing retaining clamp attached to the deck bushing lifting ring. FIG. 8 illustrates the assembly, showing the drill pipe, deck bushing retaining clamp, deck bushing lifting ring, deck bushing, bit sub, breakout wrench, drill bit, and bit breakout basket.

As shown in FIG. 9, the drill string may be raised, thereby lifting the deck bushing out of the opening in the deck. As the drill string is raised, it is ensured that the load of the deck bushing retaining clamp is distributed as evenly as possible. Additionally, the deck bushing should not be raised with a kinked or twisted chain. The drill string is raised until sufficient clearance exists for a bit breakout basket 32 to be placed into the deck well 31, as shown in FIG. 10.

The drill string is then lowered until the drill bit 33 is seated in the bit breakout basket, as shown in FIG. 11. The drill bit is broken out with a breakout wrench 37, as shown in FIG. 11. After breaking out the drill bit, the drill string is raised and the used bit in the bit breakout basked is replace with a new bit, as shown in FIG. 13. The drill string is then lowered and the new drill bit attached to the drill sub 35, as shown in FIG. 14.

After raising the drill string, the bit breakout basket is removed from the deck well as shown in FIG. 15. The drill string is then lowered until the deck bushing is resting in place on the drill deck, as shown in FIG. 16. The drill string must be lowered enough so that the chains are loose enough to permit them to be unhooked from the deck bushing retaining clamp, as shown in FIG. 17. As shown in FIG. 18, the drill string is raised high enough for the deck bushing lifting ring to be removed from the deck well. The drill string is then lowered and the deck bushing secured in the deck well.

As is apparent from drawings and the above description, there are many pieces of equipment move about during a drill bit changing operation. Manual handling of clamps, spanners, and other implements raises the risk of injury to workers. Additionally, the drill sting and attached implements are suspended over the drill deck. Both of these create potential for harm to workers, such as serious injury or death. In fact, due to the potential for harm to workers, many jurisdictions have or are contemplating having safety regulations related to work under suspended equipment. In some cases, work is forbidden under suspended loads.

In addition to the precautions described above, such as ensuring that the lifting hooks are arranged in the correct orientation, other specific precautions that are taken in this operation include making sure that the swivel hooks always support the load of the deck bushing. The load should not be supported by the latch of the swivel hook, not the tip. Workers should keep their body parts clear of the pinch point between the tip of the swivel hook and the latch of the swivel hook when closing the swivel hook. Swivel hooks are not intended to rotate under load.

Regular inspection checks, including functional checks and adjustment and maintenance should be performed at regular intervals. The working load of the deck bushing retaining clamp should not be exceeded. Additionally, the deck bushing retaining clamp should be regularly inspected and removed from service if cracks, deformations or critical defects are identified. The deck bushing retaining clamp should be handled carefully and not dropped or dragged on the drill deck. If the deck bushing retaining clamp is damaged, it should be replace rather than repaired, altered, reworked, or reshaped by welding, heating, burning or bending.

SUMMARY OF THE INVENTION

Embodiments of the claimed invention include a drilling system including a drill bit. A deck bushing includes an outer housing and an inner sleeve rotatably arranged in the outer housing. The inner sleeve has an inner diameter wider than a width of the drill bit. A drop-in sleeve is configured to be inserted into the inner sleeve of the deck bushing. At least a portion of the drop-in sleeve engages the inner sleeve of the deck bushing such that a friction between the drop-in sleeve and inner sleeve of the deck bushing causes the drop-in sleeve and inner sleeve of the deck bushing to rotate together. A lifting sub is configured to be inserted into the drop-in sleeve.

Embodiments of the invention also include a method for changing a bit in a drilling apparatus. A drilling assembly including a drill string, a drop-in sleeve, a lifting sub and a drill bit is raised through a deck bushing. The drill bit is removed from the lifting sub. A new drill bit is attached to the lifting sub. The drill string is lowered until the drop-in sleeve is seated in the deck bushing.

Still other objects and advantages of the present invention will become readily apparent by those skilled in the art from the following detailed description, wherein is shown and described only the preferred embodiments of the invention, simply by way of illustration of the best mode contemplated of carrying out the invention. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, without departing from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned objects and advantages of the present invention will be more clearly understood when considered in conjunction with the accompanying drawings, in which:

FIGS. 1-19 represent aspects of a drill bit changing operation carried out with a known drilling assembly;

FIG. 20 represents elements of an embodiment of an automated deck lifter system;

FIG. 21 represents a cross-sectional view of an embodiment of a roller deck bushing;

FIGS. 22A and 22B represent an overhead view and perspective view, respectively, of the embodiment of the roller deck bushing shown in FIG. 21;

FIGS. 23B and 23B represent an embodiment of a roller cone bit and an embodiment of another bit extending through the embodiment of the roller deck bushing shown in FIG. 21;

FIG. 24 represents a cross-sectional view of an embodiment of a drop-in sleeve;

FIG. 25 represents an overhead view of the embodiment of the drop-in sleeve shown in FIG. 24;

FIG. 26 represents a cross-sectional view of the drop-in sleeve shown in FIGS. 24 and 25 and the embodiment of the roller deck bushing shown in FIG. 21;

FIGS. 27-30 represent perspective views of embodiments of a lifting sub;

FIGS. 31 a-31 c represent the embodiment of the lifting sub shown in FIG. 27 and the embodiment of the drop-in sleeve shown in FIGS. 21 and 22;

FIG. 32 represents the embodiment of the lifting sub shown in FIG. 27 and connections to a drill bit and drilling pipes;

FIG. 33 represents the embodiment of the lifting sub shown in FIG. 27, the embodiment of the drop-in sleeve shown in FIGS. 21 and 22 and connections to a drill bit and drilling pipes; and

FIGS. 34-43 represent aspects of an embodiment of a drill bit changing operation carried out with an embodiment of a drilling assembly according to the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

To address safety concerns related to potential for injury it would be desirable to have an alternative or automated system for carrying out at least some operations, such as elements of the bit replacement process set forth above. For example, it could be desirable to automate the lifting of the deck bushing from the deck. Such automation could be utilized in mining operations to address safety regulations that prohibit an operator from working beneath a suspended load. Such automation could be useful in any rotary blast-hole drilling operation what utilizes a method for changing bits that is similar to the above-described method.

As described below in greater detail, embodiments of the invention include a lifting sub, drop-in sleeve and deck bushing that eliminate the need for manually equipped clamps and spanners and to suspend the deck bushing above the bit change operation. By eliminating Embodiments of the invention permit the drill bit to pass through the deck bushing while the deck bushing remains in the drill deck. Utilizing embodiments of the invention can reduce or eliminate accidents related to working under suspended loads and manual handling of equipment. Embodiments of the invention can also reduce the time required to change out a drill bit. This will increase the operational time of a drill rig, thereby increasing productivity, decreasing operator idle time and increase profit.

FIG. 20 illustrates an embodiment of elements of an automated deck bushing lifting system 100 according to the invention. The embodiment shown in FIG. 20 includes a deck bushing 102, lifting sub 104 and drop-in sleeve 106. This embodiment is shown utilized with a tricone drill bit 108. However, elements of the claimed invention may be utilized with other types of drill bits, drill pipes and/or drill rigs. In some cases, elements may need to be scaled and/or otherwise adapted to work with other drill bits and/or drill rigs.

The embodiment of the deck bushing 102 shown in FIG. 20 is a two-part bushing. The deck bushing has an outer diameter configured to fit in the opening in the drill deck. The deck bushing 102 includes a flange 104 configured to retain the bushing in the drill deck opening. Along these lines, the drill deck opening typically is countersunk to accommodate the flange on the deck bushing.

The deck bushing typically is a two-piece design, an embodiment of which is shown in FIG. 21. The embodiment of the deck bushing 102 shown in FIG. 21 includes an outer housing 110 and an inner sleeve 112. The inner sleeve has a diameter sufficient to permit the drill bit to pass through without engaging the inner surface 114 of the inner sleeve. On the other hand, known designs utilize a deck bushing that has an inner diameter that is sized with respect to the diameter of the drill string.

The inner sleeve is designed to rotate with respect to the outer housing. To accomplish this, the outer surface 116 of the inner sleeve 112 and inner surface 117 of the outer housing 110 may include bearing races 120. Any number of bearing races as well as the size of the bearing races and diameter of the bearings 122 may be utilized that permit the inner sleeve to rotate properly within the outer housing. The embodiment of the deck bushing 102 shown in FIG. 21 includes three bearing races 118 on each of the inner sleeve 112 and outer housing 110.

The bearing races may be machined on each of the inner sleeve 112 and outer housing 110. The inner sleeve 112 and outer housing 110 may be mated together. Then, bearings may be introduced through passages 122 in the outer housing 110. Plugs 124 may then be fitted into the passages 122 to cap the passages.

The embodiment of the deck bushing shown in FIG. 21 also includes additional elements to help position and retain the inner sleeve and outer housing. For example, the embodiment of the outer housing 110 shown in Fig. includes a lip 111 extending about the upper inner edge. The lip 111 can help to position and retain the inner sleeve. Additionally, the inner sleeve may include a lip 113 extending outwardly from a lower edge of the inner sleeve 112. The lower lip may also help to position the inner sleeve and outer housing with respect to each other.

FIGS. 22 a and 22 b illustrate, respectively, overhead and perspective views of the embodiment of the deck bushing shown in FIG. 21. As shown in FIGS. 22 a and 22 b, the deck bushing may include cut-outs 117 and 119 to help locate the deck bushing in the drill deck. Accordingly, the cut-outs may engage complementary structures on the drill deck. The cut-outs may help to stop the outer flange and bearing housing from turning with the inner sleeve when the drill is in operation. As can be seen in FIGS. 23 a and 23 b, the inner sleeve of the deck bushing has an inner diameter sufficient to permit the drill bit to pass therethrough.

A drop-in sleeve 106 is designed to fit within the inner sleeve 112 of the deck bushing 102. The drop-in sleeve will translate rotation of the drill string to the inner sleeve of the deck bushing. As such, the drop-in sleeve will take up a majority of wear caused by rotating the drill pipe.

FIG. 24 illustrates an embodiment of a drop-in sleeve 106 according to the claimed invention. This embodiment has an outer diameter that permits the drop-in sleeve to fit within the inner sleeve 112 of the deck bushing 110. The outer diameter may vary depending upon the deck bushing being utilized. The drop-in sleeve has an inner diameter sized to permit the drill string to extend therethrough. As with the outer diameter, the inner diameter of the drop-in sleeve may vary depending upon the drill string utilized.

The drop-in sleeve 106 may include a tapered outer lower edge 124 to facilitate its insertion into the inner sleeve of the deck bushing. The inner lower edge 126 may also be tapered. Similarly, the upper inner edge 128 may be tapered to facilitate inserting the drill bit and drill string. The tapered surfaces of the drop-in sleeve may reduce wear and vibration on the deck bushing during drilling operations. The angle and length of the tapered surfaces may vary, depending upon the application.

The upper edge 130 of the drop-in sleeve typically includes a flange 132 configured to engage at least a portion of the deck bushing. The flange 132 may extend continuously entirely around the drop-in sleeve. Alternatively, the flange may include a plurality of flange portions that extend around the upper edge of the drop-in sleeve. FIG. 25 illustrates an overhead view of the embodiment of the drop-in sleeve shown in FIG. 24.

The embodiment of the flange shown in FIG. 22 includes an angled surface 134 configured to engage a surface of the inner housing of the deck bushing. FIG. 24 illustrates a cross-sectional view of the embodiment of the drop-in flange shown in FIGS. 22 and 23 and the embodiment of the deck bushing shown in FIG. 21. FIG. 24 shows the drop-in sleeve and inner housing 112 as they would interact during drilling operations. These embodiments engage each other such that the tapered edge of the inner housing of the deck bushing flange surface 134.

The outer diameter of the drop-in sleeve is small than the inner diameter of the inner sleeve of the deck bushing so as to provide a small clearance between the two structures. This permits the drop-in sleeve to be raised from and lowered into the deck bushing without major binding between the two structures.

On the other hand, the drop-in sleeve and the angled surfaces 134 on the drop-in sleeve and 115 on the inner sleeve 112 of the deck bushing frictionally engage each other. The frictional force is sufficient to provide translational force between the two components. As a result of the translational force, the inner sleeve of the deck bushing will rotate during drilling operations as the drop-in sleeve rotates with the rotation of the drill string.

The invention also includes a lifting sub. The lifting sub replaces the bit sub typically utilized. As such, the lifting sub will be joined to a starter, or lead, pipe in a drill string and joined to the drill bit. To make the connections, the lifting sub will include a threaded connection on both ends. The threaded connections may be male or female. Typically, one end includes a male threaded connection and the other end a female connection, which is known as a pin/box configuration. However, any combination of male and female may be utilized. In other words, a pin/pin or box/box configuration may be utilized. The lifting sub includes a lifting portion configured to lift the drop-in sleeve from the deck bushing, thereby permitting the drill bit to pass through the deck bushing.

FIG. 27 illustrates an example of a lifting sub 140 according to the invention. The embodiment of the lifting sub shown in FIG. 27 includes a body 141. A male threaded connection 142 is provided at the upper end to be attached to the lead pipe in the drill string and a female threaded connection at the lower end to be attached to the drill bit. The lifting sub may include elements typically included in bit subs currently utilized. For example, the lifting sub may include wrenching and breakout areas.

The lifting sub includes a lifting structure configured to engage the drop-in sleeve. For example, the embodiment shown in FIG. 27 includes a portion having an enlarged diameter 144. The enlarged diameter portion provides at least one surface 146 configured to engage the drop-in sleeve and lift the drop-in sleeve out of the deck bushing during bit changing. The lifting sub may include a plurality of surfaces 146 for lifting the drop-in sleeve. In other words, the enlarged diameter portion may not extend continuously about the entire lifting sub.

The oversize lifting section in the embodiment shown in FIG. 27 includes a wrenching area on opposite sides of the lifting sub. The wrenching area may extend to the side of the lifting sub eliminating the lifting surface as shown in FIG. 27. The wrenching areas may also be configured to leave lifting surfaces in the region of the wrenching areas.

One or more portions of the lifting sub may include hard-facing. Hard-facing hardens the surface of drilling tools, makes them more resistant to abrasion, corrosion, and impact, thereby prolonging the service life of the parts including hard-facing. Hard-facing may be accomplished through a coating of metal or alloy to a metal component. In some cases, the surface of a metal component could be treated to form the hard-coating. The embodiment of the lifting sub shown in FIG. 27 includes hard-facing regions 150 and 152 on the lifting section 144 and at the lower end of the lifting sub.

The lifting sub may also include additional features and/or features arranged in a different manner from the embodiment shown in FIG. 27. Along these lines, at least a portion of the outer surface of the lifting sub may include ribs. The ribs may facilitate the drilling operation by improving the flow of cuttings and drilling fluid past the lifting sub. This can greatly reduce wear and, thereby, increase the life span of the lifting sub. The ribs may also provide a more even wear pattern to the lifting sub.

The embodiment shown in FIG. 28 includes upper wrench flats 154 and lower wrench flats 156. The upper wrench flats may be the main wrench flats for engaging the lifting sub. The lifting section is provided by the lifting ribs 160. As such, the lifting ribs provide a plurality of lifting surfaces for engaging and lifting the drop-in sleeve. The lower, or secondary, wrench flats may be utilized to remove the lifting sub when it is being replaced. The lifting ribs may extend above and below the secondary wrench flats to provide stability when the lifting sub is within the hole. This embodiment of the lifting sub includes more extensive hard-facing than the embodiment shown in FIG. 27. Along these lines, the hard-facing covers a majority of the lifting sub body 140 while still maintaining an appropriate area for a breakout wrench to grip. The hard facing, or welding grooves, may be placed in areas were the dimensional integrity of sub will be best protected. These areas may be on the spanner flat edges and/or the periphery of the larger outer diameter, longitudinally and cross-sectionally on the sub.

FIG. 29 illustrates another embodiment of a lifting sub. As is apparent from this embodiment, the lifting sub may include a combination of elements and/or altered elements included in the embodiments shown in FIGS. 27 and 28. The embodiment of the lifting sub shown in FIG. 29 includes a lifting sub body 141 and oversized lifting ribs and lower wrench flats similar to the embodiment shown in FIG. 28. However, the embodiment shown in FIG. 29 includes an auto rod changing breakout section 162 that can permit use of an auto rod changing system, such as is available from Atlas Copco. This embodiment does not include upper wrench flats. Also, the auto rod changing breakout section 162 should have an outer diameter small enough to pass through the drop-in sleeve. The auto rod changing breakout section 162 typically has a same out diameter as the lifting sub body 140. A region of reduced diameter 164 may be arranged below the auto rod changing breakout section 162.

FIG. 30 illustrates a still further embodiment of a lifting sub 140 according to the invention. The embodiment shown in FIG. 30 includes roller stabilizers. The roller stabilizers include rollers 166, blocks 168 and a roller stabilizer body 170. The embodiment shown in FIG. 30 includes blocks 168 above and below the rollers 166. The rollers and blocks may include tungsten carbide inserts to reduce deviation and hole crookedness when drilling. The rollers and blocks may be particularly beneficial when utilized in angle drilling applications since the rollers and blocks can reduce a torque load on the rotary drive system. They are also particularly useful with larger diameter drill strings. The upper surfaces of the blocks above the rollers provide the lifting surface for lifting the drop-in sleeve.

As is apparent from FIGS. 27-30 is that the design of the lifting sub may vary. The design may depend upon the type of bit and type of drilling, among other factors. However, the lifting sub will include at least one lifting surface to lift the drop-in sleeve out of the deck bushing.

FIGS. 31 a, 31 b and 31 c illustrate the embodiment of the drop-in sleeve shown in FIGS. 24 and 25 and the embodiment of the lifting sub shown in FIG. 27 showing the drop-in sleeve and lifting sub alone and with the drop-in body arranged on the lifting sub. Additionally, FIG. 32 illustrates the embodiment of the lifting sub shown in FIG. 27 showing the male threaded connection 142 and female threaded connection 143. A threaded connection 145 on a drill bit 147 and a threaded connection 149 on the lead pipe 151 in a drill string are also shown. FIG. 33 illustrates the lifting sub with the drop-in sleeve attached and attached to a drill string. Along these lines, FIG. 33 illustrates the lead pipe 166, drill pipes 168 a, thread saver sub 170 and a shock sub.

Embodiments of the invention provide a much improved and safer method for changing a drill bit to be carried out. This process is illustrated in FIGS. 34—and described below. Embodiments of the invention may be utilized with existing drilling equipment, such as drilling decks without requiring any modifications. Along these lines, FIG. 34 illustrates an embodiment of a deck bushing according to the claimed invention arranged in a deck opening. As shown in FIG. 35, a sliding deck fork 174 may be extended over the lip of the deck bushing but not over the drop-in sleeve. The deck fork will help to secure the deck bushing in the deck well when raising the drill string during the bit change operation.

Next, as illustrated in FIG. 36, the drill string is raised, causing the lifting surface on the lifting sub to engage the drop-in sleeve, thereby lifting the drop-in sleeve out of the deck bushing. The drill string is raised until the drill bit clears the hydraulic break out basket if the hydraulic breakout basket is being utilized, as in the embodiment being described herein. As described above, other method and apparatuses for removing the drill bit may be employed. If hydraulic break out basket is utilized, it is positioned in the break out location as represented in FIG. 37. Otherwise, a drop-in bit break out basket 176 may be arranged in the deck bushing.

The drill string is then lowered until the drill bit is seated in the bit breakout basket as shown in FIG. 38. Next, a breakout wrench 178 may be utilized to break out the drill bit as shown in FIG. 39. Once the drill bit is broken out, the breakout wrench is removed and the drill string raised. A new drill bit is then positioned in the bit breakout basket, as shown in FIG. 40. The drill string is then lowered so that the lifting sub can be connected to the new drill bit, as shown in FIG. 41. As illustrated in FIG. 42, the drill string with the new bit attached is raised at least until the drill bit clears the bit breakout basket. The bit breakout basket is then removed from the deck bushing, as shown in FIG. 42. The drill string may then be lowered into the deck bushing, as shown in FIG. 43. As the drill string is being lowered, the drop-in sleeve will seat securely in the deck bushing.

Embodiments of the invention may be utilized with existing drill rigs without requiring any modification. As can be seen from the above, embodiments of the invention can prevent workers from working under a suspended load as currently required when utilizing a deck bushing lifting ring and deck bushing retaining clamp. Along these lines, embodiments of the invention can eliminate the need to utilized clamps and spanners for securing the deck bushing when raising the drill pipe. This helps to ensure the safety of workers, preventing soft tissue injury as well as other injuries and even death from the suspended load and/or manual handling of clamping and other tools.

The length of the sub 104 may be constrained by the height to clear the break-out system and the deck height. Along these lines, the sleeve needs to be seated in the deck bushing before the bit reaches the ground. In other words, if the bit sub is going to be longer than about 50 inches then the inner sleeve may be left hanging on the pipe instead of being seated inside the deck bushing. For various rig types, there may not be more than about 15 inches difference in deck height. If the bit were to begin drilling before sleeve is seated in the deck bushing, then cuttings will blow through the deck bush onto the deck. The cuttings flying about would create a “dust storm”, which would represent another safety hazard.

The foregoing description of the invention illustrates and describes the present invention. Additionally, the disclosure shows and describes only the preferred embodiments of the invention, but as aforementioned, it is to be understood that the invention is capable of use in various other combinations, modifications, and environments and is capable of changes or modifications within the scope of the inventive concept as expressed herein, commensurate with the above teachings, and/or the skill or knowledge of the relevant art. The embodiments described hereinabove are further intended to explain best modes known of practicing the invention and to enable others skilled in the art to utilize the invention in such, or other, embodiments and with the various modifications required by the particular applications or uses of the invention. Accordingly, the description is not intended to limit the invention to the form disclosed herein. Also, it is intended that the appended claims be construed to include alternative embodiments. 

I claim:
 1. A drilling system, comprising: a drill bit; a deck bushing comprising an outer housing and an inner sleeve rotatably arranged in the outer housing, the inner sleeve having an inner diameter wider than a width of the drill bit; a drop-in sleeve configured to be inserted into the inner sleeve of the deck bushing, wherein at least a portion of the drop-in sleeve engages the inner sleeve of the deck bushing such that a friction between the drop-in sleeve and inner sleeve of the deck bushing causes the drop-in sleeve and inner sleeve of the deck bushing to rotate together; and a lifting sub configured to be inserted into the drop-in sleeve.
 2. The drilling system according to claim 1, further comprising: bearing races on an outer surface of the inner sleeve of the deck bushing and an inner surface of the outer housing of the deck bushing; and ball bearings arranged in the bearing races.
 3. The drilling system according to claim 1, wherein an upper end of an inner surface of the inner sleeve of the deck bushing has an outwardly angled tapered edge, wherein the drop-in sleeve comprises an upper flange having an edge including a complementarily angled tapered edge engaging the tapered edge of the inner sleeve of the deck bushing.
 4. The drilling system according to claim 1, wherein a top surface of the drop-in sleeve is flush with a top surface of the deck bushing.
 5. The drilling system according to claim 1, wherein the drop-in sleeve translates rotation of a drill string to the outer housing of the deck bushing.
 6. The drilling system according to claim 1, wherein the lifting sub joins a lead pipe in a drill string to the drill bit.
 7. The drilling system according to claim 1, wherein the lifting sub comprises an oversize portion having an outer diameter greater than an inner diameter of the drop-in sleeve, such that raising the lift sub will raise the drop-in sleeve.
 8. The drilling system according to claim 7, wherein the oversize portion comprises wrenching and breakout areas.
 9. The drilling system according to claim 7, wherein the oversize portion comprises a hard facing region.
 10. The drilling system according to claim 7, wherein the oversize portion comprises a plurality of ribs configured to permit cuttings to pass up past the lifting sub.
 11. The drilling system according to claim 10, wherein the oversize portion comprises wrenching flats.
 12. The drilling system according to claim 1, wherein the lifting sub comprises at least one hard facing region
 13. The drilling system according to claim 12, wherein the at least one hard facing region comprises wrenching and breakout areas.
 14. The drilling system according to claim 12, wherein a majority of the lifting sub comprises hard facing.
 15. The drilling system according to claim 1, wherein the lifting sub comprises a plurality of ribbed sections and a plurality of non-ribbed sections.
 16. The drilling system according to claim 1, wherein the lifting sub comprises roller stabilizers comprising rollers and blocks.
 17. The drilling system according to claim 1, wherein the drill bit is a tricone bit or down the hole bit.
 18. A method for changing a bit in a drilling apparatus, the method comprising: raising a drilling assembly comprising a drill string, a drop-in sleeve, a lifting sub and a drill bit through a deck bushing; removing the drill bit from the lifting sub; attaching a new drill bit to the lifting sub; and lowering the drill string until the drop-in sleeve is seated in the deck bushing.
 19. The method according to claim 18, further comprising: arranging a bit breakout basket in the deck bushing, wherein the drilling assembly is raised to a level such that the drill bit has clearance with respect to the breakout basket; lowering the drill string until the drill bit is positioned in the bit breakout basket; breaking out the drill bit utilizing a breakout wrench; raising the drill string; replacing the drill bit in the breakout basket with a new drill bit; lowering the drill string; attaching the new drill bit to the lifting sub; raising the drill string; and remove the bit breakout basket from the deck bushing.
 20. The method according to claim 18, further comprising: extending a deck fork over a lip of the deck bushing prior to raising the drill string, the drop-in sleeve, the lifting sub and the drill bit through the deck bushing.
 21. The method according to claim 18, further comprising: positioning an hydraulic bit breakout basket into a breakout location; lowering the drill string until the drill bit is positioned in the hydraulic bit breakout basket; breaking out the drill bit; raising the drill string; replacing the drill bit in the hydraulic bit breakout basket with a new drill bit; lowering the drill string; attaching the new drill bit to the lifting sub; raising the drill string; and removing the hydraulic bit breakout basket from the breakout location. 